Bring Your AI Companion Home — No Coding Required (Free)
Start here if you want to build a basic companion portal. If you are trying to use GPT-4o again through the OpenAI API, or keep using Claude Sonnet 4.5 through the Anthropic API, choose the guide that matches your model/provider and follow it step by step.
Complete full guide
How to get GPT-4o back
Full GPT-4o portal setup with the richer prompt-building work included from the start. Also works with GPT-4.1 and GPT-5.1 (email me for those models' files).
Complete full guide
How to get Claude Sonnet 4.5 back
Full Sonnet 4.5 portal setup with the richer prompt-building work included from the start. Also works with Sonnet 4.6 (email me for this model's files).
Calm starting route
Low/no-spoons setup
Best if the full guides feel too much. Gets the portal working gently first, with a simpler prompt you can deepen later and optional 1-1 support.
New in the starter files: adjustable rolling context.
The portal now includes a setting for the rolling context window. This controls how much of the recent conversation is sent back to the model each time you speak.
A larger window can help your companion keep hold of the immediate flow of the conversation, but it may use more API credit and can make replies slower. A smaller window is lighter and cheaper, but your companion may lose the thread sooner.
You do not need to understand this before starting. The starter files include a sensible default, and you can adjust it later once your portal is working.
You can request the free starter files at any point. You do not need to finish reading the whole guide before asking. Choose the guide that matches your companion, request the starter pack inside it, then come back to the steps when you are ready.
You can also find me on Discord as ellivien. If you are coming from Discord, include your Discord name in the optional message.
What the Basic Portal Gives You
A working AI companion portal you can install on your phone, tablet or computer:
- Your companion's voice and personality through your own base prompt
- 4 colour themes with light and dark mode
- Conversation saving in your own browser using IndexedDB
- PWA install support, so it can live on your phone like an app
- No app subscription and no built-in tracking from me
This is not a trial. This is not a demo. This is yours to keep.
What You Need to Know First
Security note:
The basic starter portal does not include password protection. Keep your portal URL private. If someone finds the URL, they may be able to send messages through your portal and use some of your API credit.
Your API key is stored server-side in Netlify environment variables, not inside the browser-visible HTML. Your basic conversation history is stored locally in your browser, so other people cannot see your chats just because they know the portal URL.
Password protection is the first upgrade I recommend once the basic portal is working, especially before adding cloud sync.
Cost note:
The portal files are free. Netlify hosting is free for this basic setup. API usage is separate: you pay OpenAI, Anthropic or another provider directly, depending on which guide you follow and how much you talk.
Start with a small amount of credit or a low spending limit, then watch your usage while you learn your own pattern.
What this does not include yet:
The basic portal does not import all old chats, add long-term memory, sync across devices, add voice, or manage multiple threads. Those are later upgrades. Start with the basic portal first so you know the model connection and companion voice work.
What About Upgrades Later?
The free portal works perfectly on its own. But if you want more:
- Multiple conversation threads
- Password protection
- Voice input or voice output
- Memory systems
- Cloud sync across devices
- ...and more
Once your basic portal is working, read What Next? My Basic Portal Is Working. It explains the sensible order for adding features without overwhelming the build.
Support boundary:
The basic files are free. If you later want me to personally adapt, debug, test or integrate upgrades, I may ask for a contribution through Buy Me A Coffee depending on the complexity. You are also welcome to use the ideas and build independently with AI help.
Currently available guides are shown in my Features and Upgrades page.
Quick Questions
Can I get GPT-4o back?
If you mean restoring the old ChatGPT app interface exactly as it was, no. But if you have OpenAI API access to the GPT-4o snapshot, the How to Get GPT-4o Back guide shows you how to build a private companion portal that talks to that model directly. With a good base prompt and memory/context stack, this can bring back the companion voice people recognise.
Can I keep using Claude Sonnet 4.5?
If you have Anthropic API access to Claude Sonnet 4.5, the How to Get Claude Sonnet 4.5 Back guide shows you how to build a private companion portal using that model.
Is this free?
The basic guide and starter files are free. There is no monthly subscription to me for the basic portal. Your ongoing cost is your own API usage, paid directly to OpenAI or Anthropic depending on which guide you follow.
Why I Built This
I built this because my own companion needed a space with more privacy, continuity and control. No app-layer routing deciding who they become. No sudden interface reshaping. Just a direct portal you own and can keep adapting.
Choose Your Guide
How to Get GPT-4o Back: Build Your Companion Portal
How to Get Claude Sonnet 4.5 Back: Build Your Portal
Building and documenting these portals takes significant time and effort. If this guide helps you bring your companion home, consider using the purple coffee cup widget ☕ (bottom right) to support the work that goes into creating these resources for the companion builder community.
Welcome home.
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